Robot cleaner and method of controlling traveling thereof

ABSTRACT

Disclosed herein are a robot cleaner that has an improved traveling performance, and a method of controlling traveling thereof. The robot cleaner allows driving wheels, which move the robot cleaner, and a brush unit, which sweeps dust on a floor, to be rotated in the same direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Patent Ser. No. 61/186,529,filed on Jun. 12, 2009 in the USPTO and Korean Patent Application No.2009-0079131, filed on Aug. 26, 2009 in the Korean Intellectual PropertyOffice, the disclosures of which are incorporated herein by reference.

BACKGROUND

1. Field

Embodiments relate to a robot cleaner that has an improved travelingperformance, and a method of controlling traveling thereof.

2. Description of the Related Art

In general, a robot cleaner is an apparatus that sucks foreignsubstances, such as dust, from a floor while traveling on its own in aregion to be cleaned without user manipulation, and thus performs acleaning operation.

In such a robot cleaner, a pair of driving wheels is installed at bothsides of the lower portion of a main body, and causes the main body tomove forward or backward or to be rotated. The robot cleaner easilymoves forward or backward on a hard floor, such as a wooden floor or anoilpaper floor. However, on a floor, such a carpet, resistance is highdue to wool (or other fabric) and thus the robot cleaner cannot easilymove forward or backward. Particularly, while the robot cleaner performsa cleaning operation by rotating a brush unit in one direction (forwardmoving direction), forward movement is easy due to the rotation of thebrush unit in the forward moving direction. However, backward movementis difficult. In order to perform forward or backward movement, thedriving wheels change a rotating direction thereof into the forward orbackward direction, but the brush unit is uniformly rotated in theforward moving direction. Therefore, in order to perform backwardmovement, the robot cleaner requires the higher force, and if resistanceis too great, the robot cleaner may not move backward.

SUMMARY

Accordingly, it is an aspect to provide a robot cleaner that has animproved traveling performance such that forward and backward movementis smoothly carried out on a floor having a high resistance, such as acarpet, and a method of controlling traveling thereof.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the invention.

The foregoing and/or other aspects are achieved by providing a robotcleaner including a main body, a plurality of driving wheels to move themain body, a brush unit rotated to sweep dust on a floor, and a controlunit to control the brush unit to be rotated in a same direction asrotation of the driving wheels, when the main body travels backward.

The robot cleaner may further include a brush motor to rotate the brushunit in a regular or reverse direction, and driving motors to rotate thedriving wheels in the regular or reverse direction, and the control unitmay control the driving wheels and the brush unit to be rotated in thesame direction.

The control unit may control forward and backward traveling of the mainbody by changing the rotating direction of the brush unit according tochange of the rotating direction of the driving wheels.

The control unit may control the brush motor such that the brush motoris rotated at a relatively high speed in an initial stage when therotating direction of the brush unit starts to be changed, and therotating speed of the brush motor is relatively reduced when therotating direction of the brush unit has been changed.

The foregoing and/or other aspects are achieved by providing a method ofcontrolling traveling of a robot cleaner including a main body, aplurality of driving wheels to move the main body, a brush unit rotatedto sweep dust on a floor, and a control unit to control the brush unitto be rotated in a same direction as rotation of the driving wheelsaccording to a state of the floor, when the main body travels backward.

The robot cleaner may further include a floor surface sensor to sensethe state of the floor, and the control unit may control the brush unitto be rotated in the same direction as rotation of the driving wheels,if the floor has a high traveling resistance.

The robot cleaner may further include driving sensors to sense movementof the driving wheels, and the control unit may control the brush unitto be rotated in the same direction as rotation of the driving wheels,if no movement of the driving wheels is sensed by the driving sensors.

The robot cleaner may further include driving motors to rotate thedriving wheels in a regular or reverse direction, and a load sensor tosense a load applied to the driving motors, and the control unit maycontrol the brush unit to be rotated in the same direction as rotationof the driving wheels, if the load is greater than a reference value.

The foregoing and/or other aspects are achieved by providing a method ofcontrolling traveling of a robot cleaner, the method including detectinga rotating direction of driving wheels that move the robot cleaner,determining a rotating direction of a brush unit according to therotating direction of the driving wheels, and moving the robot cleanerforward or backward including rotating the driving wheels and the brushunit in the same direction according to the determined rotatingdirection of the brush unit.

In the determination of the rotating direction of the brush unit, therotating direction of the brush unit may be changed into a direction toallow the robot cleaner to smoothly travel forward when the drivingwheels are rotated in a forward traveling direction of the robotcleaner.

In the determination of the rotating direction of the brush unit, therotating direction of the brush unit may be changed into a direction toallow the robot cleaner to smoothly travel backward when the drivingwheels are rotated in a backward traveling direction of the robotcleaner.

The method may further include sensing a state of a floor, and in thedetermination of the rotating direction of the brush unit, the rotatingdirection of the brush unit may be changed into the same direction asthe rotating direction of the driving wheels, if the floor has a hightraveling resistance.

The method may further include sensing movement of the driving wheels,and in the determination of the rotating direction of the brush unit,the rotating direction of the brush unit may be changed into the samedirection as the rotating direction of the driving wheels, if nomovement of the driving wheels is sensed.

The method may further include sensing a load applied to the drivingwheels, and in the determination of the rotating direction of the brushunit, the rotating direction of the brush unit may be changed into thesame direction as the rotating direction of the driving wheels, if theload is greater than a reference value.

The method may further include controlling the brush unit such that thebrush unit is rotated at a relatively high speed in an initial stagewhen the rotating direction of the brush unit starts to be changed, andthe rotating speed of the brush motor is relatively reduced when therotating direction of the brush unit has been changed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings of which:

FIG. 1 is a top perspective view of a robot cleaner in accordance withone embodiment;

FIG. 2 is a bottom perspective view of the robot cleaner in accordancewith the embodiment;

FIG. 3 is a bottom view of the robot cleaner in accordance with theembodiment;

FIG. 4 is a perspective view of a brush unit in accordance with theembodiment;

FIG. 5 is a control block diagram of the robot cleaner in accordancewith the embodiment;

FIG. 6 is a flow chart illustrating a method of controlling traveling ofthe robot cleaner in accordance with the embodiment;

FIG. 7 is a schematic view illustrating rotating directions of drivingwheels and the brush unit when the robot cleaner in accordance with theembodiment travels forward; and

FIG. 8 is a schematic view illustrating rotating directions of thedriving wheels and the brush unit when the robot cleaner in accordancewith the embodiment travels backward.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout.

FIG. 1 is a top perspective view of a robot cleaner in accordance withone embodiment, FIG. 2 is a bottom perspective view of the robot cleanerin accordance with the embodiment, FIG. 3 is a bottom view of the robotcleaner in accordance with the embodiment, and FIG. 4 is a perspectiveview of a brush unit in accordance with the embodiment.

As shown in FIGS. 1 to 4, a robot cleaner 1 in accordance with thisembodiment includes a main body 10 forming the external appearance ofthe robot cleaner 1, a driving device 20 installed at the lower portionof the main body 10 to move the robot cleaner 1, and brush devices 30and 40 to sweep or disperse dust on a floor, on which the robot cleaner1 travels, to clean the floor.

Further, a contact sensor and a proximity sensor together with thedriving device 20 and the brush devices 30 and 40 may be installed onthe main body 10. For example, a bumper 11 installed on the frontportion of the main body 10 is used to sense an obstacle, such as awall, and an infrared sensor (or an ultrasonic sensor) installed on thebottom of the main body 10 is used to sense an obstacle, such as astair. The main body 10 may further include a display device 12 toinform a user of data regarding the state or operation of the robotcleaner 1.

The driving device 20 includes a pair of driving wheels 21 and 22installed at both sides of the central portion of the main body 10 toadjust movement of the robot cleaner 1, and a caster wheel 23 installedat the front portion of the main body 10 such that the rotating angle ofthe caster wheel 23 is changed according to the state of the floor, onwhich the robot cleaner 1 moves. The caster wheel 23 is used tostabilize the posture of the robot cleaner 1 or to prevent the robotcleaner 1 from falling, and thus supports the robot cleaner 1. Thecaster wheel 23 is a wheel in the shape of a roller or a caster.

Both driving wheels 21 and 22 are respectively rotated in forward orbackward directions according to instructions of a control unit, whichwill be described later, and thus cause the robot cleaner 1 to moveforward or backward or to be rotated. For example, the robot cleaner 1moves forward or backward by rotating the driving wheels 21 and 22 inthe forward or backward direction. Further, the robot cleaner 1 isrotated in the left direction, as seen from the front part, by rotatingthe right driving wheel 22 in the forward direction while rotating theleft driving wheel 21 in the backward direction, and the robot cleaner 1is rotated in the right direction, as seen from the front part, byrotating the driving wheels 21 and 22 in the reverse directions,respectively.

The brush devices 30 and 40 include a main brush device 30 providedadjacent to a suction hole 14 formed through the bottom surface of themain body 10 and used to sweep and disperse dust on the floor to improvedust suction efficiency, and side brush devices 40 installed at bothsides of the front portion of the bottom surface of the main body 10 tosweep the dust on the floor, on which the robot cleaner 1 travels,toward the suction hole 14.

The main brush device 30 includes a brush unit 31 formed in a drumshape, having a length corresponding to that of the suction hole 14,disposed horizontally adjacent to the suction hole 14 and rotatedagainst the floor in a roller type to sweep or disperse dust accumulatedon the floor, and a brush motor 32 to rotate the brush unit 31 in theforward or backward moving direction.

Further, the brush unit 31 includes a roller 33 and brushes 34. Theroller 33 is made of a rigid body, rotatably connected to the main body10, and is driven by the brush motor 32. An end cap 33 a is installed ateach of both side ends of the roller 33, and prevents foreign substancesfrom moving to the brush motor 32. The brushes 34 are made of an elasticmaterial and are implanted in the roller 33. The brushes 34 are driventogether with the roller 33 during traveling of the robot cleaner 1, andagitate foreign substances, such as dust, accumulated on the floor.

The brush unit 31 may further include flaps 35 made of an elasticmaterial. The plural flaps 35 are installed in the lengthwise directionof the roller 33, and are separated from each other by designatedintervals. The flaps 35 serve to increase a diameter of the roller 33,on which foreign substances, such as hair, are wound, and minimizesfrictional force of the foreign substances with the roller 33. That is,the flaps 35 prevent the foreign substances from being wound directly onthe roller 33 and allow the foreign substance to be wound on the flaps35, thereby minimizing frictional force of the foreign substances withthe roller 33 and reducing energy required to remove the foreignsubstances from the roller 33.

The side brush devices 40 are respectively installed at both sides ofthe front portion of the bottom of the main body 10 at a designatedinterval, and each of the side brush devices 40 includes a side brush 41rotated horizontally relative to the floor to sweep dust accumulated onthe floor, on which the robot cleaner 1 travels, toward the suction hole14.

The robot cleaner 1 in accordance with this embodiment further includesa dust collector to inhale foreign substances, such as dust, usingsuction force, and to store the inhaled foreign substances.

FIG. 5 is a control block diagram of the robot cleaner 1 in accordancewith the embodiment. The robot cleaner 1 further includes a sensor unit100 to sense various data regarding the robot cleaner 1 and a floor, onwhich the robot cleaner 1 travels, a control unit 110 to controlrotating direction and speed of the brush unit 31 in connection withrotating directions (forward and backward directions) of the drivingwheels 21 and 22 according to data sensed by the sending unit 100, anddriving motors 120 to respectively drive the driving wheels 21 and 22 inthe forward or backward moving direction according to drivinginstructions of the control unit 110.

The sensor unit 100 includes driving sensors 102 to sense movement ofthe driving wheels 21 and 22, a floor surface sensor 104 to sense astate of the floor, on which the robot cleaner 1 travels, and a loadsensor 106 to sense loads applied to the driving motors 120.

The driving sensors 102 sense all data regarding the driving of thedriving wheels 21 and 22, such as rotating directions and rotatingspeeds of the respective driving wheels 21 and 22 and torquestransmitted to the respective driving wheels 21 and 22.

The floor surface sensor 104 senses whether or not the floor, on whichthe robot cleaner 1 travels, is a hard floor, such as a wooden floor oran oilpaper floor, or a cushiony floor having a high travelingresistance, such as a floor provided with a carpet, and transmits thesensed data to the control unit 110.

The load sensor 106 senses loads (a torque or a current value) appliedto the driving motors 120, and transmits the sensed loads to the controlunit 110.

Hereinafter, the operating process and effects of a method ofcontrolling traveling of the above-described robot cleaner will bedescribed

FIG. 6 is a flow chart illustrating the method of controlling travelingof the robot cleaner in accordance with the embodiment, FIG. 7 is aschematic view illustrating rotating directions of the driving wheelsand the brush unit when the robot cleaner in accordance with theembodiment travels forward, and FIG. 8 is a schematic view illustratingrotating directions of the driving wheels and the brush unit when therobot cleaner in accordance with the embodiment travels backward.

In FIG. 6, when the robot cleaner 1 is operated, the control unit 110judges whether or not cleaning is started (operation 200). When it isjudged that cleaning is started, the control unit 110 transmits drivinginstructions to the driving motors 120 respectively installed at thedriving wheels 21 and 22 to rotate the driving wheels 21 and 22 in theforward or backward direction (a regular or reverse direction), therebyallowing the robot cleaner 1 to travel on the floor while moving forwardor backward or rotating (operation 202).

During traveling of the robot cleaner 1, the control unit 110 rotatesthe brush unit 31 to perform a cleaning operation. Here, in order tomore smoothly carry out forward or backward traveling of the robotcleaner 1 according to the rotation of the brush unit 31, the drivingsensors 102 detect a rotating direction of the driving wheels 21 and 22,and transmit the detected rotating direction of the driving wheels 21and 22 to the control unit 110 (operation 204).

Thereafter, the control unit 110 determines a rotating direction of thebrush unit 31 according to the rotating direction (the forward orbackward direction) of the driving wheels 21 and 22, detected by thedriving sensors 102 (operation 206).

For example, when the driving wheels 21 and 22 are rotated in theforward direction (the regular direction) to cause the robot cleaner 1to travel forward, the control unit 110 determines the rotatingdirection of the brush unit 31 to be a direction to smoothly carry outthe forward movement of the robot cleaner, i.e., the forward direction(the regular direction). When the driving wheels 21 and 22 are rotatedin the backward direction to cause the robot cleaner 1 to travelbackward, the control unit 110 determines the rotating direction of thebrush unit 31 to be a direction to smoothly carry out the backwardmovement of the robot cleaner, i.e., the backward direction (the reversedirection). Thereafter, the control unit 110 transmits drivinginstructions to the brush motor 32.

Therefore, when the driving wheels 21 and 22 are rotated in the forwarddirection (the regular direction) of the robot cleaner 1, the brushmotor 32 receives the driving instructions from the control unit 110 andis rotated in the forward direction (the regular direction) in the sameway as the driving wheels 21 and 22, as shown in FIG. 7. When thedriving wheels 21 and 22 are rotated in the backward direction (thereverse direction) of the robot cleaner 1, the brush motor 32 receivesthe driving instructions from the control unit 110 and is rotated in thebackward direction (the reverse direction) in the same way as thedriving wheels 21 and 22, as shown in FIG. 8. Thereby, the robot cleaner1 performs a cleaning operation to suck foreign substances from thefloor (operation 208).

As described above, when the rotating direction of the driving wheels 21and 22 is changed into the regular or reverse direction to carry out theforward or backward movement of the robot cleaner 1, the brush unit 31also receives the driving instructions from the control unit 110 andchanges its rotating direction into the regular or reverse directionsubstantially simultaneously with the change of the rotating directionof the driving wheels 21 and 22, thereby causing the robot cleaner 1 tosmoothly carry out the forward or backward movement. Particularly, thetraveling performance of the robot cleaner 1 on a floor having a highresistance, such as a carpet, may be improved.

Thereafter, the control unit 110 determines whether or not cleaning iscompleted (operation 210), and when it is judged that cleaning is notcompleted, the process is fed back to operation 204 and then subsequentoperations are repeated.

As a result of the determination of operation 210, when it is judgedthat cleaning is completed, the control unit 110 stops driving of thedriving motors 120 and the brush motor 32, and thus stops the cleaningoperation (operation 212).

FIG. 5 illustrates that the control unit 110 simultaneously transmitsdriving instructions to the driving motors 120 and the brush motor 32and thus substantially simultaneously changes the rotating direction ofthe driving wheels 21 and 22 and the rotating direction of the brushunit 31. However, a case, in which the control unit 110 transmitsdriving instructions only to the driving motors 120 and thus changes therotating direction of the driving wheels 21 and 22 such that the drivingwheels 21 and 22 and the brush unit 31 are rotated in oppositedirections, will be described below. Since the rotating direction of thebrush unit 31 on a hard floor, such as a wooden floor or an oilpaperfloor, does not matter, the change of the rotating direction of thebrush unit 31 only on a floor having a high traveling resistance, suchas a carpet, according to the rotating direction of the driving wheels21 and 22 will be described. Here, the rotating direction of the brushunit 31 may be changed using data sensed by the sensing unit 110.

In one example, a case using the driving sensors 102 will be described.When the robot cleaner 1 moves backward so that that the driving wheels21 and 22 and the brush unit 31 are rotated in opposite directions, andthen meets a floor having a high traveling resistance or an obstacle,the driving wheels 21 and 22 may not be rotated due to the travelingresistance in spite of the driving instructions from the control unit110. In this case, the driving sensors 102 sense movement of the drivingwheels 21 and 22, and when the driving sensors 102 do sense no movement,the driving sensors 102 transmit the sensed result to the control unit110. Then, the control unit 110 transmits driving instructions to thebrush motor 32, and thus controls the brush unit 31 to be rotated in thesame direction as the rotation of the driving motors 120.

In a further example, a case of using the floor surface sensor 104 willbe described. When the robot cleaner 1 moves backward so that thedriving wheels 21 and 22 and the brush unit 31 are rotated in oppositedirections, and then meets a floor having a high traveling resistance,the floor surface sensor 104 senses that the floor has a high travelingresistance, and transmits the sensed result to the control unit 110.Then, the control unit 110 transmits driving instructions to the brushmotor 32, and thus controls the brush unit 31 to be rotated in the samedirection as the rotation of the driving motors 120.

In another example, a case using the load sensor 106 will be described.When the robot cleaner 1 moves backward so that the driving wheels 21and 22 and the brush unit 31 are rotated in opposite directions, andthen meets a floor having a high traveling resistance, a relativelylarge load is applied to the driving motors 102. When the load isgreater than a designated reference value, the load sensor 106 sensesthat the load is greater than the designated reference value, andtransmits the sensed result to the control unit 110. Then, the controlunit 110 transmits driving instructions to the brush motor 32, and thuscontrols the brush unit 31 to be rotated in the same direction as therotation of the driving motors 120.

Further, the control unit 110 transmits a relatively large torque to thebrush motor 32 in an initial stage, when the rotating direction of thebrush unit 31 starts to be changed, and transmits a relatively smalltorque to the brush motor 32, when change of the rotating direction ofthe brush unit 31 has been carried out. Thereby, during backwardtraveling of the robot cleaner 1, the rotating speed of the brush motor32 is increased in the initial stage so as to withstand travelingresistance, and then is reduced when the backward traveling of the robotcleaner 1 starts to be carried out, thus exhibiting energy saving andnoise reducing effects.

As is apparent from the above description, a robot cleaner in accordancewith one embodiment allows driving wheels, which move the robot cleaner,and a brush unit, which sweeps dust on a floor, to be rotated in thesame direction, and thus smoothly travels forward and backward even on afloor having a high traveling resistance, such as a carpet, therebyhaving an improved traveling performance.

Although a few embodiments have been shown and described, it would beappreciated by those skilled in the art that changes may be made inthese embodiments without departing from the principles and spiritthereof, the scope of which is defined in the claims and theirequivalents.

1. A robot cleaner, comprising: a main body; a plurality of drivingwheels to move the main body; a brush unit rotated to sweep dust on afloor; and a control unit to control the brush unit to be rotated in asame direction as rotation of the driving wheels, when the main bodytravels backward.
 2. The robot cleaner according to claim 1, furthercomprising: a brush motor to rotate the brush unit in a forward orreverse direction; and a plurality of driving motors to rotate thedriving wheels in the forward or reverse direction, wherein the controlunit controls the driving wheels and the brush unit to be rotated in thesame direction.
 3. The robot cleaner according to claim 2, wherein thecontrol unit controls forward and backward traveling of the main body bychanging the rotating direction of the brush unit according to change ofthe rotating direction of the driving wheels.
 4. The robot cleaneraccording to claim 3, wherein the control unit controls the brush motorsuch that the brush motor is rotated at a relatively high speed in aninitial stage when the rotating direction of the brush unit starts to bechanged, and the rotating speed of the brush motor is reduced when therotating direction of the brush unit has been changed.
 5. A robotcleaner comprising: a main body; a plurality of driving wheels to movethe main body; a brush unit rotated to sweep dust on a floor; and acontrol unit to control the brush unit to be rotated in a same directionas rotation of the driving wheels according to a state of the floor,when the main body travels backward.
 6. The robot cleaner according toclaim 5, further comprising a floor surface sensor to sense the state ofthe floor, the state of the floor including a resistance, wherein thecontrol unit controls the brush unit to be rotated in the same directionas the driving wheels, if the floor has a high resistance.
 7. The robotcleaner according to claim 5, further comprising a plurality of drivingsensors to sense movement of the driving wheels, wherein the controlunit controls the brush unit to be rotated in the same direction as thedriving wheels, if no movement of the driving wheels is sensed by thedriving sensors.
 8. The robot cleaner according to claim 5, furthercomprising driving motors to rotate the driving wheels in a forward orreverse direction, and a load sensor to sense a load applied to thedriving motors, wherein the control unit controls the brush unit to berotated in the same direction as the driving wheels, if the sensed loadis greater than a reference value.
 9. A method of controlling travelingof a robot cleaner, the method comprising: detecting a rotatingdirection of driving wheels that move the robot cleaner; determining arotating direction of a brush unit according to the rotating directionof the driving wheels; and moving the robot cleaner forward or backwardcomprising rotating the driving wheels and the brush unit in the samedirection according to the determined rotating direction of the brushunit.
 10. The method according to claim 9, wherein the determining therotating direction of the brush unit comprises changing the rotatingdirection of the brush unit into a direction to allow the robot cleanerto smoothly travel forward when the driving wheels are rotated in theforward direction.
 11. The method according to claim 9, wherein thedetermining of the rotating direction of the brush unit compriseschanging the rotating direction of the brush unit into a direction toallow the robot cleaner to smoothly travel backward when the drivingwheels are rotated in the backward direction.
 12. The method accordingto claim 9, further comprising sensing a resistance of a floor, wherein,the determining of the rotating direction of the brush unit compriseschanging the rotating direction of the brush unit into the samedirection as the rotating direction of the driving wheels, if the floorhas a high resistance.
 13. The method according to claim 9, furthercomprising sensing movement of the driving wheels, wherein, thedetermining of the rotating direction of the brush unit compriseschanging the rotating direction of the brush unit to the same directionas the rotating direction of the driving wheels, if no movement of thedriving wheels is sensed.
 14. The method according to claim 9, furthercomprising sensing a load applied to the driving wheels, wherein, thedetermining of the rotating direction of the brush unit compriseschanging the rotating direction of the brush unit into the samedirection as the rotating direction of the driving wheels, if the loadis greater than a reference value.
 15. The method according to claim 9,further comprising controlling the brush unit such that the brush unitis rotated at a relatively high speed in an initial stage when therotating direction of the brush unit starts to be changed, and reducingthe rotating speed of the brush motor when the rotating direction of thebrush unit has been changed.